1.5°C marks the point, say many scientists, where there is a real danger of serious ‘tipping points’ in the world’s climate. Photograph: Alex Hofford/EPA

Special UN report will offer comprehensive assessment of impacts of a 1.5°C rise in global warming on sea level, coral bleaching and biodiversity

April 18, 2016 — Scientists from around the world will contribute to a major UN report on how global temperatures can be held to a rise of 1.5°C and what the impact might be on sea level rises, the bleaching of corals and biodiversity.

The special report, from the Intergovernmental Panel on Climate Change (IPCC), will assess all the available peer-reviewed science along with other special reports on how land and oceans are being affected by climate change. These will look at the melting of ice in polar and mountain regions, as well as the impact of climate change on cities and food supplies.

“We now have a roadmap for the next comprehensive assessment which will be published in 2022, in good time for the global stocktake by governments in 2023,” said Hoesung Lee, chair of the panel, in Nairobi.

The 1.5°C report was requested by governments meeting at the Paris climate talks in December where countries unexpectedly agreed to “pursue efforts” to limit warming to 1.5°C above pre-industrial levels. 1.5°C marks the point, say many scientists, where there is a real danger of serious “tipping points” in the world’s climate. Temperatures have already risen 1°C and show little sign of slowing.

“Before the Paris meeting governments were focussing on [a rise of ] 2°C. The latest assessment by the IPCC showed that some serious risks to corals and sea-level rise emerge at 1.5°C. But there was not much available [science] on these topics. There is a lot we need to find out about 1.5°C. We are ready to embark on this,” said Lee.

“Limiting warming to 1.5°C will be a significant challenge,” said Myles Allen, Professor of Geosystem Science at Oxford university’s Environmental Change Institute (ECI).

“In a nutshell, it means we have to reduce emissions twice as fast as we would have done to limit warming to 2°C – and that was already looking challenging. Inevitably, people are already starting to ask if it is worth it. These are big tough questions, and we haven’t much time to answer them, so the academic community needs to step up.”

The University of Oxford will host a major 1.5°C conference later this year to bring together climate experts, researchers, policymakers, businesses and members of civil society from around the world.

The IPCC meeting in Nairobi comes ahead of next week’s UN meeting in New York when 130 countries will sign the Paris agreement. “It will be the biggest number of countries ever to have signed an international agreement. It will be ratified when countries that account for at least 55% of global emissions countries have signed,” said a spokesman for the IPCC.

The IPCC is responsible for providing governments with authoritative overviews of the latest climate science. Every seven years it produces a “synthesis” report which sums up the scientific knowledge on climate change – the most recent one warned global warming would have “severe, widespread, and irreversible impacts”.